{"m30":{"schemaVersion":1,"id":"WTC1-N-M30-NIST-retained-fragments","tower":1,"face":"north","sourcePanel":"A133:94-97","recoveredPanel":"M-30","appliesTo":["postimpact-base","postimpact-severe"],"source":{"citation":"NIST NCSTAR 1-3C Volume I, pp.98-99,101; Figs.2-14 (p.39),3-2 (p.121)","url":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-3cv1.pdf","pdfPagesOneBased":[252,191,190,188,168],"sourcePhotoCredit":"Figure 2-14: Roberto Rabanne/Corbis, 2001; Figure 3-2: NIST","localPdf":"sources/NCSTAR1-3Cv1.pdf","sectionCitation":"NIST NCSTAR 1-3B final, Table 4-1 p.51 identifies M-30 type123; Table3-5 p.14 gives 7/16in side plates and1/4in webs; spandrels3/8in."},"supported":{"retainedColumns":[132,133],"retainedRegion":"Lower portions at and below the floor-95 spandrel, in the upper floor-94 region; relatively undeformed apart from the spandrel.","column132Fracture":"At the stiffener associated with the top of the floor-95 spandrel.","column133Fracture":"At a slightly lower elevation associated with the floor-95 concrete slab.","column133PlateFold":"Local outer-web and spandrel plate portions bent inward nearly 90 degrees.","column133OuterWebThicknessIn":0.25,"spandrelThicknessIn":0.375,"timing":"General recovered appearance agrees with pre-collapse photographic evidence; local extra damage during/after collapse is possible."},"calibration":{"modelAxes":"x east, z south, floor ordinate converted through shared floor-height schedule; north-wall inward is +z","columnCenters":{"132":6.666666666666667,"133":10},"columnPitchFt":3.3333333333333335,"lowerSpliceFloor":94.4,"lowerSpliceBasis":"Align to the existing FEMA nominal stagger for the missing C132-134/F94.4-97.4 panel, not a measured recovered-piece length.","floor95SpandrelTopAboveSlabFt":1.125,"floor95SpandrelBottomBelowSlabFt":3.2083333333333335,"spandrelBasis":"Existing model's sourced 52in spandrel depth and 12.5in center below floor; determines top/bottom planes.","nativePageImagePixels":[2751,3729],"figure214CropPixelsOnNativePage":[787,1715,1961,2938],"annotatedPageImagePixels":[917,1243],"figure214ApproxBoundsOnAnnotatedPage":[268,585,647,971],"imageRole":"Photo confirms retained lower fragments and local interruption. Perspective and partial occlusion prevent a metrically rectified pixel-to-world transform; member numbering and floor planes supply model registration."},"geometry":{"nominalColumnDepthFt":1.1666666666666667,"defaultSidePlateThicknessIn":0.4375,"columns":[{"number":132,"centerXFt":6.666666666666667,"lowerFloor":94.4,"sideTopFloor":95.09375,"outerWebTopFloor":95.09375,"innerWebTopFloor":95.09375,"outerWebThicknessIn":0.25},{"number":133,"centerXFt":10,"lowerFloor":94.4,"sideTopFloor":94.98611111111111,"outerWebTopFloor":94.94,"innerWebTopFloor":94.94,"outerWebThicknessIn":0.25}],"spandrel":{"outlineXFloor":[[6.083333333333334,94.73263888888889],[10.583333333333334,94.73263888888889],[10.583333333333334,94.94],[9.416666666666666,94.94],[9.416666666666666,94.98611111111111],[7.25,95.09375],[6.083333333333334,95.09375]],"thicknessIn":0.375,"placement":"inner face","extentStatus":"Representative torn remnant between the two explicitly recovered columns. Its side boundary, taper and exact surviving area are not a NIST measurement."},"foldedPlateLips":[{"id":"C133-outer-web-lip","column":133,"xBoundsFt":[9.416666666666666,10.583333333333334],"hingeFloor":94.94,"plateFace":"outer","lengthFt":0.75,"angleInwardDeg":88,"thicknessIn":0.25},{"id":"C133-spandrel-lip","column":133,"xBoundsFt":[9.416666666666666,10.583333333333334],"hingeFloor":94.94,"plateFace":"inner","lengthFt":0.75,"angleInwardDeg":88,"thicknessIn":0.375}],"defaultInnerWebThicknessIn":0.25},"uncertainty":{"retainedIdentityConfidence":"high","fractureFloorConfidence":"high","inwardLocalPlateFoldConfidence":"high for direction and approximate near-right angle","retainedLengthConfidence":"moderate; uses source floor description and existing nominal splice registration","spandrelOutlineConfidence":"representative low precision","lipLengthFtRange":[0.35,1.25],"lipAngleDegRange":[80,100],"column133FractureElevationRelativeToFloor95FtRange":[-0.5,0.25],"lowerSpliceFloorSensitivityRange":[94.25,94.55],"sourceConflict":"FEMA trace omits this nominal panel entirely; this addition is a separately labeled later-NIST fragment layer. It must not be described as a change to or tracing of the FEMA source polygon.","doNotRestore":["column134","upper columns above their documented fracture region","complete three-story M30 panel","a 90-degree bend of either whole column"]}},"wtc2Exit":{"schemaVersion":1,"id":"WTC2-N-exit-observed-fragments","tower":2,"face":"north","renderFloorBounds":[80.4,82.6],"appliesTo":["postimpact-base","postimpact-severe"],"sources":[{"id":"NIST1-2-Fig7-75","citation":"NIST NCSTAR 1-2, pp.278-279, Figs.7-74 and7-75","url":"https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=101012","localPdf":"sources/NCSTAR1-2.pdf","pdfPagesOneBased":[392,393],"role":"Column identities, six-foot severed lengths, retained outer web at254, broken bolt/unloaded257-258, intact neighboring controls."},{"id":"NIST1-3C-Fig2-32","citation":"NIST NCSTAR 1-3C Volume I, p.23 and Fig.2-32, p.54","url":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-3cv1.pdf","localPdf":"sources/NCSTAR1-3Cv1.pdf","pdfPagesOneBased":[268,237],"role":"Pre-collapse photograph with floor/column labels; detached254 outer web over slightly more than two floors;257-258 broken at floor81 and ends bent outward slightly."},{"id":"NIST1-5A-p386","citation":"NIST NCSTAR 1-5A, Chapter9, p.386, discussion of Fig.9-79","url":"https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=101030","role":"Independently identifies253 cut near the top of the81st-floor window and254 distorted; nearby82-floor spandrel between251-252 appears torn."}],"sourcePixelReferences":{"figure232UprightImage":"analysis/exterior-gap-review/NIST1-3C_exit-detail-237-upright.png","imagePixels":[2200,1621],"northFaceCropPixels":[995,340,1760,1125],"columnLabelsAtPhotoBottomApprox":[[259,1066,1124],[258,1144,1124],[257,1215,1124],[256,1289,1124],[255,1360,1124],[254,1424,1124],[253,1488,1124],[252,1560,1124],[251,1637,1124],[250,1716,1124]],"missingSectionCalloutsCropPixels":[[322,450,370,559],[512,490,572,580]],"outerWeb254VisibleApproxCenterlineCropPixels":[[348,268],[367,336],[397,391],[414,495],[426,611]],"role":"Indices identify source labels and visible features for review. Oblique perspective and smoke prevent a reliable direct pixel-to-world displacement fit. Numbered columns and text/floor references supply world registration.","photoCredit":"2001 Lyle Owerko/Wonderlust (Fig.2-32); 2001 Richard Drew/AP (Fig.7-74)"},"worldRegistration":{"xFormula":"(columnNumber - 230) * 40 / 12","zReferenceFt":-103.58333333333333,"northOutwardSign":-1,"nominalColumnDepthFt":1.1666666666666667,"representativePlateThicknessIn":0.375,"window81TopFloor":81.73263888888889,"windowTopBasis":"Shared model: floor82 slab minus the3.208333ft lower edge of its52in spandrel. NCSTAR1-5A p386 locates253 fracture near the top of this window.","slotBottomFloor":81.23263888888889,"slotTopFloor":81.73263888888889,"slotLengthFt":6,"slotRegistrationStatus":"Representative fit: anchor the reported six-foot loss downwards from the stated window-top fracture. The exact end coordinates are not surveyed.","slotVerticalTranslationUncertaintyFt":[-1,1]},"features":[{"id":"WTC2-N-C253-six-foot-severance","column":253,"xFt":76.66666666666667,"operation":"omit complete box over slot only","floorBounds":[81.23263888888889,81.73263888888889],"lengthFt":6,"evidenceConfidence":"high identity and length; moderate window-region placement; inferred precise ends"},{"id":"WTC2-N-C254-retained-outer-web","column":254,"xFt":80,"operation":"omit inner web and side plates over the six-foot slot; retain the outer web as a separate continuous plate","floorBounds":[81.23263888888889,81.73263888888889],"retainedPart":"outer web plus visible flange tips; no full box section through the slot","sourceLoadState":"outer web intact but not load bearing","outerWebDetachedHeight":"slightly more than two floors","optionalDetachedWebDisplay":{"floorBounds":[80.4,82.6],"maximumOutwardOffsetFt":0.25,"shape":"smooth outward bow, zero at both display ends","displayStatus":"Representative envelope only; source supports detachment over more than two floors, but not these endpoints or bow amplitude.","boundsSensitivity":{"lowerFloorRange":[80,81],"upperFloorRange":[82,83]},"maximumOffsetFtRange":[0,0.5]},"evidenceConfidence":"high retained outer-web identity and non-load-bearing statement; moderate window placement; low precise detached-web envelope"},{"id":"WTC2-N-C257-broken-splice","column":257,"xFt":90,"operation":"retain column; show local broken bolt splice with slightly outward bent ends","referenceFloor":81,"representativeGapFt":0.08333333333333333,"bendTransitionLengthFt":1,"maximumOutwardOffsetFt":0.15,"sourceLoadState":"unloaded","evidenceConfidence":"high broken splice/floor reference and slight outward direction; gap and bend magnitude representative","magnitudeRanges":{"gapFt":[0.02,0.15],"outwardFt":[0.05,0.3]}},{"id":"WTC2-N-C258-broken-splice","column":258,"xFt":93.33333333333333,"operation":"retain column; show local broken bolt splice with slightly outward bent ends","referenceFloor":81,"representativeGapFt":0.08333333333333333,"bendTransitionLengthFt":1,"maximumOutwardOffsetFt":0.15,"sourceLoadState":"unloaded","evidenceConfidence":"high broken splice/floor reference and slight outward direction; gap and bend magnitude representative","magnitudeRanges":{"gapFt":[0.02,0.15],"outwardFt":[0.05,0.3]}}],"preserve":[{"columns":[252,255,259],"state":"intact and straight in Fig7-75;252 qualified as appears intact"},{"column":256,"state":"slight outward bow explicitly inconclusive; do not assign it as confirmed damage"},{"column":300,"state":"No corner column at81st-floor engine exit; existing spandrel connecting259/301 intact per1-3C Fig2-31. Do not fabricate a broken corner column from this opening."}],"conflictsAndIntegration":["NCSTAR1-3C p23 prose calls the fully cut pair254/255. NCSTAR1-2 Fig7-75 labels253/254 and says255 intact; NCSTAR1-5A p386 independently identifies253 cut and254 distorted. Prefer253/254 for geometry and preserve the prose conflict in metadata.","Existing damage_state.json extra_removals entry for253/254/257/258 has render:false and remains unsuitable for blanket removal. Add these local source-qualified fragment rules instead.","Current generic panel-splice phase is representative. The explicit observed81st-floor failed splice for257/258 should override the local visual joint; do not alter the whole face schedule.","The snapshot in1-5A Fig9-79 is late in the sequence. Its text attributes this column damage to aircraft-debris exit, while hanging slab objects discussed alongside it may have later timing and should not automatically be imported into the immediate impact state.","All partial boxes and retained outer-web strips must replace overlapping intact column geometry; a retained web must not be added on top of a still-solid column."]},"additionalStructuralObservations":[{"id":"WTC2-N-F82-C251-C252-spandrel-tear-observation","floor":82,"columns":[251,252],"source":"NIST NCSTAR 1-5A Chapter9 p.386, Fig.9-79 p.387 (part2 PDF90\u201391)","source_url":"https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=101030","observation":"Spandrel at the base of floor82 between C251 and C252 appears torn. NIST says aircraft impact is the likely cause but cannot establish it with certainty.","firstEvidencePhotoTime":"09:58:37","renderWholeSpandrelRemoval":false,"reason":"Photo and text establish a possible local tear, not loss of the full bay or a metrically resolved fracture contour. Do not remove the full spandrel or its seats. Add this localized evidence to the inspection record; retained shape needs further photo registration before geometry can be defensibly cut."}]}